Modern consumer electronics particularly personal portable devices, such as cellular phones, digital cameras, and music players, require increasing integrated circuit chip content to fit an ever-shrinking physical space as well as increasing performance.
The demands for smaller, higher performance semiconductor devices have motivated the development of new techniques for producing smaller and less expensive semiconductor devices. One of these technologies involves packaging the integrated circuit chip in as small a form factor as possible and manufacturing the integrated circuit chip as efficiently as possible.
Usually, many individual devices are constructed on the same wafer. When the devices are separated into individual rectangular units, each takes the form of an integrated circuit chip. In order to interface a chip with other circuitry, it is common to mount it with lead fingers and individually connect pad on the chip to the lead fingers using extremely fine wires. The assemblies are then packaged by individually encapsulating them in molded plastic or ceramic bodies.
Integrated circuit packaging technology has shown an increase in the number of chips mounted on a single circuit board or substrate that parallels the reduction in the number of components needed for a circuit. This results in packaging designs that are more compact, in the physical size and shape of a device, and in a significant increase in overall integrated circuit density. However, integrated circuit density continues to be limited by the area available for mounting chips on a substrate.
To condense the packaging of individual devices, packages have been developed in which more than one device can be packaged at one time at each package site. Each package site is a structure that provides mechanical support for the individual integrated circuit devices. It also provides one or more layers of interconnect lines that enable the devices to be connected electrically to surrounding circuitry.
In some cases, multi-chip devices can be fabricated faster and more cheaply than a corresponding single integrated circuit chip, that incorporates all the same functions. Some multi-chip modules have been found to increase circuit density and miniaturization, improve signal propagation speed, reduce overall device size, improve performance, and lower costs.
However, such multi-chip modules can be bulky. Package density is determined by the area required to mount a chip or module on a circuit board. One method for reducing the board size of multi-chip modules and thereby increase their effective density is to stack the chips vertically within the module or package. Such designs are improvements over prior packages that combined several chips and associated passive components side by side in a single, horizontal layer.
However, multi-chip modules, whether vertically or horizontally arranged, can also present problems because they usually must be assembled before the chips and chip connections can be tested. That is, because the electrical bond pads on a chip are so small, it is difficult to test chips before assembly into a package.
When chips are mounted and connected individually, the chip and connections can be tested, and a known-good-unit (“KGU”) free of defects is then assembled into larger circuits. A fabrication process that uses KGU is therefore more reliable and less prone to assembly defects introduced due to bad chips. With conventional multi-chip modules, the chip cannot be individually identified as KGU before final assembly.
Despite the advantages of recent developments in semiconductor fabrication and packaging techniques, there is a continuing need for improving packaging methods, systems, and designs.
Thus, a need still remains for an integrated circuit package in package system to provide a lower profile, increase the number of devices in a package system, and reduce delamination, adhesive, and adhesion failures. In view of the increasing demand for improved density of integrated circuits and particularly portable electronic products, it is increasingly critical that answers be found to these problems.
Solutions to these problems have been long sought but prior developments have not taught or suggested any solutions and, thus, solutions to these problems have long eluded those skilled in the art.